A seasoner is a word used to describe someone or something that adds flavor or zest to something. There are many synonyms that can be used to describe a seasoner, including spice, condiment, flavoring, and seasoning. Some other synonyms include herb, seasoning agent, zest, essence, and aroma. Each of these words describes something that adds a distinct taste or fragrance to food or other items. For example, spices such as cumin or cinnamon can be added to create a certain flavor, while condiments like mustard or ketchup can add tanginess or sweetness. Ultimately, the synonym that is used depends on the specific type of seasoning being added.